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| [[Image:1pzy.jpg|left|200px]] | | [[Image:1pzy.jpg|left|200px]] |
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| {{STRUCTURE_1pzy| PDB=1pzy | SCENE= }} | | {{STRUCTURE_1pzy| PDB=1pzy | SCENE= }} |
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| '''W314A-BETA1,4-GALACTOSYLTRANSFERASE-I COMPLEXED WITH ALPHA-LACTALBUMIN IN THE PRESENCE OF N-ACETYLGLUCOSAMINE, UDP AND MANGANESE'''
| | ===W314A-BETA1,4-GALACTOSYLTRANSFERASE-I COMPLEXED WITH ALPHA-LACTALBUMIN IN THE PRESENCE OF N-ACETYLGLUCOSAMINE, UDP AND MANGANESE=== |
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| ==Overview==
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| beta1,4-Galactosyltransferase-I (beta4Gal-T1) undergoes critical conformational changes upon substrate binding from an open conformation (conf-I) to the closed conformation (conf-II). This change involves two flexible loops: the small (residues 313-316) and the long loop (residues 345-365). Upon substrate binding, Trp314 in the small flexible loop moves towards the catalytic pocket and interacts with the donor and the acceptor substrates. For a better understanding of the role played by Trp314 in the conformational changes of beta4Gal-T1, we mutated it to Ala and carried out substrate-binding, proteolytic and crystallographic studies. The W314A mutation reduces the enzymatic activity, binding to substrates and to the modifier protein, alpha-lactalbumin (LA), by over 99%. The limited proteolysis with Glu-C or Lys-C proteases shows differences in the rate of cleavage of the long loop of the wild-type and mutant W314A, indicating conformational differences in the region between the two proteins. Without substrate, the mutant crystallizes in a conformation (conf-I') (1.9A resolution crystal structure), that is not identical with, but close to an open conformation (conf-I), whereas its complex with the substrates and alpha-lactalbumin, crystallizes in a conformation (2.3A resolution crystal structure) that is identical with the closed conformation (conf-II). This study shows the crucial role Trp314 plays in the conformational state of the long loop, in the binding of substrates and in the catalytic mechanism of the enzyme.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12927542}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12927542 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12927542}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Protease digetion]] | | [[Category: Protease digetion]] |
| [[Category: Substrate binding]] | | [[Category: Substrate binding]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:41:55 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 18:14:43 2008'' |
